sensors Mode-S transponder

A716A2

ICAO 24-bit transponder address · allocated to United States

Currently assigned to N556KM · operated by FIFTY-ONE AIR LLC

Hex
A716A2
Octal
51613242
Decimal
10,950,306
Country
US
Tail
N556KM
Type
F2TH
No current signal · last broadcast 1d ago
Flights observed
3
Distinct callsigns
1
Country
US
Last broadcast
1d ago

Last known position

Most recent position reported by Mode-S A716A2.

Country allocation

The ICAO 24-bit address A716A2 falls within the block assigned to United States (US) by ICAO Annex 10, Volume III. Every aircraft registered in United States receives a permanent address from this block at the time of registration; the address stays with the airframe even if the aircraft is re-registered to a different operator within the country.

Callsign history 1 distinct

Callsign Airline Flights Last seen
EJM556 - 3 2026-04-13

Recent flights last 3

DateFlightRouteTakeoffLandingDuration
2026-04-13 EJM556 SLC → AUS Apr 13, 13:25 UTCApr 13, 15:40 UTC2h 15m
2026-04-12 EJM556 - Apr 12, 18:50 UTCApr 12, 20:15 UTC1h 25m
2026-04-12 EJM556 - Apr 12, 17:15 UTCApr 12, 17:30 UTC15m

About Mode-S

A Mode-S transponder code (also called an "ICAO 24-bit address" or "hex code") is a 6-character hexadecimal identifier permanently assigned to an aircraft when it's first registered. Unlike callsigns (which change with each flight) or registrations (which can change if an aircraft is sold internationally), the Mode-S address stays with the airframe for the life of the aircraft in that country.

Every ADS-B transmission from an aircraft includes its Mode-S address, making it the most reliable way to identify a specific airframe. Flight-tracking services like Apparatus use the Mode-S address as the primary key for tying position broadcasts, callsigns, and ownership records together.

Prefer a tail-number view? See the N556KM page for operator, model, and routing details .

Mode-S A716A2 frequently asked

What is Mode-S code A716A2?
A716A2 is an ICAO 24-bit transponder address. Allocated to United States. Assigned to N556KM.
Where is Mode-S A716A2 registered?
Mode-S code A716A2 is allocated to United States (US). All aircraft registered there receive a Mode-S address from a fixed block defined by ICAO Annex 10.
Is A716A2 broadcasting right now?
No active broadcast right now. Last signal was 1d ago.
Hex, octal, and decimal Mode-S codes: what's the difference?
The same 24-bit identifier expressed in different bases: hex A716A2, octal 51613242, decimal 10,950,306.
What flights does A716A2 operate?
Mode-S A716A2 has broadcast 1 distinct callsign, including EJM556.